Many neuromodulatory systems of the brain have been implicated in higher order functions, both cognitive and emotional. To help identify their specific sites and modes of action, we have undertaken studies in macaques to localize several neuromodulator receptors of interest and to determine some of their functional properties. The levels of mu opiate receptors in different cortical sensory areas was found to be linked to the rates of protein phosphorylation in the F1 band in these same areas; since phosphorylation of the F1 protein has been correlated with learning and memory, the results suggest that opiates may exert local control over the learning-related phosphorylation process. Cerebral localization of benzodiazepine and beta-carboline receptors indicate that the two receptor types are distributed nearly identically, implying that both drugs act on the same brain regions to produce their effects on anxiety. The cortical laminar distribution of nicotinic and muscarinic cholinergic binding sites suggests that nicotinic receptors probably modulate sensory processing, whereas muscarinic receptors are more likely to be involved in sensory information storage.